Device For Uv-Irradiating Of Human&#39;s Cutaneous Covering Vertical Solarium

ABSTRACT

This invention relates to medical engineering, more particularly, to therapeutically applicable light-irradiating devices used for treatment of skin diseases, as well as for generating vitamin D 3  and preventing various forms of osteoporosis. In addition, the device can find application at beauty shops and sunless-tanning studios for cosmetic purposes. 
     A technical problem to be solved by the present invention resides in increasing the efficiency of the device. 
     The problem is solved due to reducing the amount of the lamps to ‘n’ and substituting the plain circular cylinder-shaped reflector by a reflector comprised of 2n alternating areas of involute cylinder-shaped surfaces of two types integrated into a single surface, the evolutes of said surfaces are closed curves which limit the convex transverse sections of the lamp and absorber in contemplation, respectively, which reflector is interposed between the lamps and the solarium body. 
     Hence carrying the invention into effect enables one to reduce electric power consumption of the vertical solarium three- to fourfold, the value of the UV-radiation flux remaining unaffected.

The present invention relates to medical engineering, more particularly,to therapeutically applicable light-irradiating devices used fortreating skin diseases, such as psoriasis, Kaposi's disease, vitiligo,and others), as well as for generating vitamin D₃ and preventing variousforms of osteoporosis. In addition, the device can find utility whenused at beauty shops and sunless-tanning studios for cosmetic purposes.

One prior-art device for UV-irradiation of human's cutaneous covering,wherein the user assumes the standing posture, operating in theUV-radiation spectrum A (315-400 nm) (hereinafter referred to as “UF-Aspectrum”)—vertical solarium available SunVision by the firm ALISUN(both from the Netherlands) (cf. the supplement below, by themanufacturer's prospectus entitled “New vertical solarias Sun-Vision”,said device comprising a body having a door and accommodating 48fluorescent lamps for taking sunless tan, each being 2 m long and havinga power output of 180 W. The lamps are spaced apart at an equal angularpitch round a common axis which is at the same time the solarium's axis,arranged parallel thereto and equidistantly therewith; in addition, thelamps have a common mirror reflector which is interposed between thelamps and the body and is spaced 10 mm apart from the lamp surface; thereflector appears as a circular cylinder having an inner mirroredsurface. The device is further provided with an air-cooling system forthe lamps and user. However, the device under discussion suffers fromtoo a low efficiency and high power input.

Estimation Of The Prototype Efficiency

Taking into consideration an axial symmetry of the vertical solarium inquestion, user's ability to assume various positions during the session,and bearing in mind that the breadth of human's shoulder and pelvis in amajority of cases approximates 500 mm, it would be true and correct toimagine the user as a conventional convex radiation absorber appearingas a circular cylinder 500 mm in diameter and arranged coaxially withthe solarium.

The simplifying assumptions thus made result in an axisymmetrical designmodel of a vertical solarium for the studying of which it is sufficientto consider a bidimensional problem (FIG. 1).

Let us assume that portion of the UV radiation emitted by a lamp 1 whichis incident upon an absorber 2 either directly from said lamp or afterhaving been reflected to be a useful one, and its share in a totalradiation is assumed to be an optical efficiency of the lamp(hereinafter referred to as “efficiency”) which is numerically equal tothe efficiency of the whole solarium on account of symmetry of the model(loss for ventilation, decorative boost lighting, and so on are left outof the given evaluation). In terms of illumination power the solariumefficiency is described by the formula:

(1) Efficiency=100%(Φ_(UVdir)+Φ_(UV) _(ref))/φ_(UV), wherein:

Φ_(UVdir)—direct (non-reflected) UV radiation flow incident upon theabsorber;

Φ_(UVdir) = ∫_(λ₁)^(λ₂)Φ_(UVdir)λ;

ΦUV_(ref)—reflected UV radiation flow incident upon the absorber;

Φ_(UVref) = ∫_(λ₁)^(λ₂)Φ_(UVref)λ;

Φ_(UV)—UV radiation flow emitted by the lamp (ratio between the energytransferred by the radiation and the transfer time exceedingconsiderably the oscillation period, W):

Φ_(UV) = ∫_(λ₁)^(λ₂)Φ_(UV)λ;

wherein:

Φλ_(UV)—spectral flow density (radiation flow per unit wavelengthinterval, W/nm).

Forasmuch as the lamp radiates light in every direction (i.e.,diffusely) within the whole wavelength range of interest to us, equation(1) may be written in terms of angular values:

$\begin{matrix}{{Efficiency} = {\frac{\alpha_{{dir}.{av}.} + {\alpha_{{ref}.{av}}K_{{ref}.}}}{2_{\Pi}}100\%}} & (2)\end{matrix}$

wherein:

α_(dir.av)—average magnitude of angle α_(pr.);

α_(dir.)—angle at which absorber is seen from the point on the surfaceof the luminous element of the lamp;

α_(ref.av)—average magnitude of angle α_(ref.);

α_(ref.)—angle at which an airgap between lamps im reflector 3 is seenfrom the point on the surface of the incandescent body of the lamp;

K_(ref.)—total reflection coefficient of the reflector.

It is a phosphor layer that serves as the luminous element influorescent lamps made use of in solaria, said layer following thegeometric shape of the gas-discharge tube, and angles α_(dir.av) andα_(ref.av) are found from the following relationships:

$\begin{matrix}{\alpha_{{dir}.{av}} = \frac{\int_{- \phi_{0}}^{\phi_{0}}{{\alpha (\phi)}\ {\phi}}}{2\; \phi_{0}}} & (3) \\{\alpha_{{dir}.{av}} = \frac{2{\int_{\phi_{1}}^{\phi_{2}}{{\alpha (\phi)}\ {\phi}}}}{\; {\phi_{2} - \phi_{1}}}} & (4)\end{matrix}$

The limits of integration in formula (3) φ_(o) and _φ_(o) are angularcoordinates of “points of sunset” E and F, i.e., such points on the lampsurface that lie on common tangents EP and CF of the lamp and absorber,respectively. All points on the lamp surface having coordinate φ arelarger than φ_(o) but less than 2π-φ_(o) do not irradiate the absorberdirectly. The nature of dependence of angle α_(dir). on the angularcoordinate of the radiating point on the surface of the lamp luminouselement are illustrated in FIG. 2.

φ_(o)=π/2+Arcsin((R−r)/L)   (5)

Angular coordinates of the “points of sunset” G and H for calculatingα_(ref.av) are also determined on the basis of the solarium geometrywhereby they are therein omitted. A diagram of pathways of the lightrays between the lamps after their having been reflected from thereflector is shown in FIG. 3. The nature of dependence of angle α_(ref).On the position of a point on the lamp surface is presented in FIG. 4.

Having applied formulas (2), (3) and (4) for estimating efficiency ofthe prototype having the following dimensions: L=440 mm, R=250 mm, r=20mm, we shall obtain:

α_(dir.av)=70.52° (1.23 rad)

α_(ref.av)=8.95°×2=17.890 (0.31 rad)

K_(ref)=1 (assuming the mirror to be ideal) Efficiency=24.59%.

Herein Φ_(UVref)=0.0497 Φ_(UV) (0.0447 Φ_(UV) for a mirror from purealuminum having K_(ref)=0.9. However, reflector contribution to theefficiency of the device is but rather small, since any ray that hasfailed to get incident upon the absorber after first reflection will yetnot be absorbed by the absorber, because the lamp-to-lamp airgaps aresmall and the light ray has no opportunity to have reflection twice. Itis easy to verify the fact by making rather simple geometricconstructions.

The results of estimations performed on the basis of a bidimensionalmodel are corroborated by the results of measurement of irradiance inUV-A spectral range carried out by the authors on the prototype.

Hence we have ascertained that efficiency of the prototype is as low as25% and that the reflector made use of therein directs as low as 5% ofthe total lamp radiation onto the absorber.

Thus, the present invention is aimed at solving a technical problemwhich resides in attaining higher efficiency of the device.

The technical problem of the invention is solved by reducing the amountof the lamps used and substituting the circular cylinder-shapedreflector made use of in the prototype, by a reflector comprised of 2nalternating areas of involute cylinder-shaped surfaces of two typesintegrated into a single surface, appearing from the evolutes of whichare closed curves which limit the convex transverse sections of theabsorber and lamp in contemplation.

The essence of the invention is illustrated by a schematic diagram ofthe device with 12 lamps (FIG. 5) and a luminous flux equal to that inthe 48-lamp prototype. A cross-section shown in FIG. 6 is conventionallyenlarged.

Principal structural components of the solarium are as follows: avertically oriented body 4 having a door 5, n fluorescent lamps fortaking sunless tan, said lamps being spaced apart at an equal angularpitch round a common axis which is at the same time the solarium's axis,arranged parallel thereto and equidistantly therewith. A mirrorreflector 3 is interposed between the body 4 and the lamps 1, saidreflector appearing as a cylinder coaxial with the body and comprised of2n alternating areas of involute cylinder-shaped surfaces of two types.

The areas of the first-type surface are disposed immediately behind thelamps 1 (curve BΓ

, FIG. 6) and appear as a portion of an involute cylinder-shaped surfacegenerated by moving a straight line parallel to the solarium body axislengthwise the straight line segments of the unlike branches of theinvolute of a closed curve which limits the convex transverse section ofthe lamp.

The areas of the second-type surface are interposed between the lamps(curve ABB in FIG. 6) and appear as a portion of an involutecylinder-shaped surface generated by moving a straight line parallel tothe solarium axis lengthwise the segments of the unlike branches of aconvex closed curve which limits the transverse section of theconventional absorber.

The areas of the first-type and second-type surfaces are mated gently atthe point B. It is due to the fact that the normal to an involute isthereto a tangent to the evolute by definition, that the herein-proposedreflector shape provides for both complete radiation emergence bypreventing it from being reflected back onto the lamp, and totalreflection to the absorber of all rays which have failed to get incidentthereupon directly from the lamp.

The herein-proposed solarium may have as high efficiency as about 100%.It is noteworthy that efficiency of the solarium depends on the numberof lamps used, since some of the luminous rays are absorbed after havinggot incident upon other lamps. Thus, for an ideal reflector the solariumhaving 6 lamps features an efficiency of 98.4%, the solarium with 12lamps, an efficiency of 89.2%, and the solarium with 16 lamps, anefficiency of 79.7%.

Consequently, in order to get absorber illuminance in the UF-A spectrumequal to that of the prototype, it suffices 12 lamp of the same power,i.e., carrying the present invention into effect enables one to reduceelectric power consumption approximately 3.6 times compared with theprototype.

1. A device for UV-irradiating of human's cutaneous covering, i.e., avertical solarium comprising a cylinder-shaped body closed along theperimeter thereof provided with a door and accommodating ‘n’ fluorescentlamps for taking sunless tan, said lamps being spaced apart at an equalangular pitch round an axis which is at the same time the solarium'saxis, and being arranged parallel thereto and equidistantly therewith,said device further comprising a cylinder-shaped mirror reflector whichis coaxial with the solarium body and is interposed between the lampsand said body, CHARACTERIZED in that the reflector is comprised of 2nalternating areas (integrated into a cylinder) of first-type andsecond-type involute cylinder-shaped surfaces the evolutes of which areclosed curves which limit the convex transverse sections of the lamp andconventional absorber, respectively, each area of the first-type surfaceis disposed immediately behind each lamp and appears as a portion of aninvolute cylinder-shaped surface generated by moving a straight lineparallel to the solarium body axis lengthwise the involute of a closedcurve which limits the convex transverse section of the lamp, and eacharea of the second-type surface is disposed between the lamps and is aportion of an involute cylinder-shaped surface generated by moving astraight line parallel to the solarium body axis lengthwise the involuteof a closed curve which limits the transverse section of theconventional absorber.